1. Field of the Invention
The present invention relates to an image capturing apparatus that captures, records and reproduces still images and moving images, and more particularly to an image capturing apparatus that has a micro lens array in front of an image sensor, which is a constituent element of the image capturing apparatus.
2. Description of the Related Art
Conventionally, there are many image capturing apparatuses, such as electronic cameras, that record and reproduce still images and moving images captured with a solid-state image sensor such as a CCD or a CMOS by using a memory card having a solid-state memory element as a recording medium.
As an example of a technique for such image capturing apparatuses, an image capturing apparatus has been proposed that has a configuration in which a micro lens array where the lenses are arranged such that each corresponds to a plurality of pixels is arranged in front of a solid-state image sensor, whereby information regarding the incidence direction of light rays that are incident on the image sensor is also obtained (see, for example, Ren. Ng et al. “Light Field Photography with a Hand-Held Plenoptic Camera”, Stanford Tech Report CTSR 2005-02).
Such an image capturing apparatus is capable of, in addition to generating ordinary captured images based on an output signal from each pixel, reconfiguring images focused at arbitrary distances by performing predetermined image processing on the captured images.
However, image capturing apparatuses, not only those having a micro lens array described above, have the following problems. Specifically, it is often the case that image sensors used in commonly-used image capturing apparatuses have an OB area that is used to determine a reference level of the output signal and that includes a plurality of optical black pixels (OB pixels) that are optically shielded from light. When the OB pixels are arranged within an effective pixel area that receives light from the subject, the light signal of the pixel area cannot be received, and therefore the OB pixels are often arranged in the periphery of the effective pixel area such as the upper side, the left side of the effective pixel area, and so forth, rather than within the effective pixel area.
However, no consideration has been given to the OB area in image capturing apparatuses having a micro lens array comprising micro lenses, each of which corresponds to a plurality of pixels, such as those described in the embodiments given in the present specification.
Also, if the reference level varies two-dimensionally within the capture surface, it is difficult to determine the reference level of the effective pixel area from the output signal from the OB area in the periphery, and as a result it may cause degradation of the obtained images.